Lessons Learned

These are the immediate reasons for the second sacrifice of the Space Shuttle program. But again, was there an overarching reason that caused this disaster? And was there an overall reason for the losses of both spaceplanes? The answer, to both questions, is yes. As with Challenger, the clustering of the stack led to the foam impact. Vertical launch of spaceplanes is not a good idea, especially when clustering of the stack is used, because it creates bad interactions between major components. This happened to both Challenger and Columbia, and it happened during launch in both cases. Paraphrasing Murphy's Law, if anything can fall onto a spaceplane at launch, then it will. This incident is no doubt one of the major reasons NASA is returning to conventional launch architecture in the Orion spacecraft, with the crew capsule at the top of the Ares stack, topped only by a launch abort system.

The lessons to be learned by the designers of spaceplanes should be these:

1. Avoid solid rocket boosters in or near a spaceplane.

2. Avoid clustering large components around a spaceplane.

3. Avoid vertical launches.

4. Use only fully reusable designs.

We owe it to these 14 brave astronauts, who gave their lives in primitive spaceplanes, to follow these simple rules. Rule number two would seem to rule out piggyback spaceplanes altogether. A winged HTHL booster could be construed as a "large component" clustered around a spaceplane. And this is true. Piggyback spaceplanes are not the best, for more reasons than one, in my humble opinion.

In principle, a Space Shuttle could be launched directly off the back of its 747 carrier, but in that case it would have to carry its propellants internally, or in small side-mounted ETs. The added weight would likely place a terrific burden on the 747, and the Shuttle would probably not make orbit, in any case, before it ran out of fuel. Its payload capability would also be severely degraded, probably relegating it to a passenger vehicle only.

The logistics involved in piggyback schemes are immense. This is illustrated by the fact that whenever the Shuttle lands at an alternate landing site, and requires a piggyback ride back to Cape Canaveral (Fig. 7.4), the cost to the taxpayer is an extra $1 million. The Shuttle first needs to be carefully lifted onto the back of the 747 using the "mate-demate device," securely attached, and then carefully flown cross-country in a series of hops designed to avoid all hazards. Both air traffic congestion and poor weather must be avoided during the transfer. The crash of a 747 while ferrying a billion-dollar Orbiter would be nothing short of scandalous.

These factors will certainly be considered when designing future two-stage-to-orbit HTHL spaceplanes, such as those favored by Bristol Spaceplanes of Bristol, England. The technical, logistical, and financial challenges in this approach are enormous. Right off the bat, in order to develop a working TSTO spaceplane that operates from a runway, two separate vehicles must be designed, engineered, and built. This immediately doubles the complexity, cost, and risk. Then they need to

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Fig. 7.4 Space Shuttle Atlantis leaves Edwards AFB, California, atop its Boeing 747 carrier on July 1, 2007 (courtesy NASA)

be mated in some manner that allows for operational efficiency. The booster stage has to support the weight not only of itself and its load of propellant, but also of its fully loaded and fueled piggyback plane. Without huge resources of capital and manpower, the likelihood of the piggyback concept being developed in the near future looks grim. We will nevertheless take a close look at the Bristol Spaceplanes design concept, because it is a design that could work, in principle. But first, we have a story of a Slavic snowstorm to tell.

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